1. Field of the Invention
The present invention relates to a development device for developing an electrostatic latent image formed on an image carrying member into a visible image, a process cartridge incorporating the development device, and an image forming apparatus, such as a multifunctional machine including at least one of a copier, a printer, a facsimile machine, and a plotter, which includes either one of the development device and the process cartridge.
2. Discussion of the Background Art
The above type of the development device is configured, for example, such that a development roller functioning as a developer carrying member and a supply roller functioning as a developer supplying member are rotated in contact with each other to supply a one-component developer stored in a development casing from the supply roller to the development roller. The developer supplied onto the development roller is spread into a thin layer and adhered to an electrostatic latent image formed on a photoconductor by an electric field generated by a developing bias voltage. The development roller and the supply roller are in contact with each other, with the rotary shaft of each of the rollers set to a predetermined position.
When the supply roller is brought into contact with the development roller, both the supply roller and the development roller compress, that is, deform due to the contact. The amount of such compression varies depending on such factors as the distance separating the shafts of the supply roller and the development roller and the outer diameters of the supply roller or the development roller. As a result, the force of contact between the rollers fluctuates, and an undesirable phenomenon such as an increase in motor torque occurs. That is, excessive pressure contact between the rollers causes the increase in torque and can result in motor failure, while insufficient pressure contact causes insufficient toner supply and a resultant decrease in image density, i.e., poor image quality.
To overcome the above-described problem by providing reliably stable contact between the rollers, the manufacturing precision of the rollers needs to be improved in terms of the shapes and the materials used, and techniques and skills to improve assembly precision are required.